2010-09-02

Spirit Sol 592

Just in front of Spirit are a couple of tasty-looking rocks -- concave, with some kind of striations, almost as if they were wheel prints. At the SOWG there's a lengthy discussion about them. At issue is whether we should stay and IDD them -- MI at least, possibly with APXS -- or drive on and possibly return for this later.

Driving away and coming back later is not something we do often. But apparently there's already one target they've pushed onto the return stack, some rock called "Irvine," and this could become another.

The reason they're eager to leave is simply one of timing. We've already performed the first half of a long-baseline-stereo observation, taking a bunch of pictures of the valley beyond Husband Hill. The other half of that experiment is where we drive about 10m away and take pictures of the same terrain from the other vantage point. It's like having two eyes set ten meters apart, which provides fantastic stereo coverage. And all this will be important for our future exploration.

But if we don't go ahead and do the drive, we'll be sitting in this spot for the weekend -- the extended, Labor Day weekend. The obvious compromise, doing a touch-and-go, is ruled out because of time and flash volume constraints. And while these rocks are intriguing, they're not worth spending five sols on.

That's particularly true in light of the continuing southward motion of the sun. In the next hundred sols or so, the energy curve will start to strongly favor south-facing slopes, which means we want to be climbing down the far side -- the south side -- of this hill before too much longer. And we have a lot of science and reconnaissance to do between now and then.

This all adds up to what should be an obvious decision: do the more important stereo imaging now, and come back to these nifty rocks later if there's time. But Ed Guinness, the SOWG chair thisol, is trying to get this across to the particularly wishy-washy scientists who are advocating staying, and he doesn't just take charge and push forward, as some other chairs would do in his place. So this discussion takes maybe twenty minutes, half an hour.

Eventually there's a compromise. All we have now is HAZCAM imagery, which isn't good enough to help us decide whether to return. So they'll PCAM the rocks before leaving, giving us much better data for that decision. Even this, however, turns into an extended discussion. How many filters? We don't have time for that many. We can't see it from the PCAM's right eye, so we'll have to back off before we use those filters and take the image mid-drive. Oh, now you don't want the right-eye filters? And so on.

When at last the time comes to name this target, one wag suggests "Indecision." But they don't call it that, of course.

What with the extended-mix vacillation, we almost miss the press conference. This is Steve Squyres and Chris Leger and Ray Arvidson and Jake Matijevic arranged around some guy I don't know, who turns out to be the NASA guy in charge of Mars exploration.

John turns to me. "Is Chris the only rover planner who's been in a press conference?"

"Yeah," I say. "I think it's because he's the only one who owns a tie."

Steve is up first. "Today is day 591 of our 90-day mission," he begins. He goes on to sum up the progress of both vehicles, emphasizing Spirit's arrival at the summit of Husband Hill. He shows off the first three-fourths of the 360-degree PCAM panorama from the top. And he and Ray announce that as Spirit ascended Husband Hill, she found definite proof of water in Gusev Crater. He reveals that we've returned ten gigabytes of data per rover so far. But the thing I think I'll always remember from this press conference is a picture Steve Photoshopped to show the scale of Husband Hill. He took the original color PCAM image of the Columbia Hills, cast around for some familiar object that was about the same height as Husband Hill, and put that object in the image in front of the hill. That object is the Statue of Liberty.

One of the last questions they take is for the NASA HQ guy: will the rovers continue to receive funding? Well, what can the guy say? "Yes, now that you've seen this spectacular image and we've learned there's irrefutable evidence of water, we're pulling the plug"? Of course not. Instead, he notes that we already have funding allocated through September of next year, with six-month reviews. "And as long as they keep doing good science, we'll keep funding them," is the substance of it.

John Callas, watching this with us in the SOWG room, pipes up, "Everybody write that down!"

[Next post: sol 597 (Opportunity sol 577), September 7.]

Courtesy NASA/JPL-Caltech. The front HAZCAM view showing the rocks we were thinking about exploring. I don't think we ever had time for them, though.